Table 5.

Panel regression test results of IMS and IMS² on ROA and ROE.

	Coefficient	t-statistics	p-value
Panel A: ROA (fixed effects)
Constant	−0.2012	−0.2754	0.7832
IMS	0.1096	2.4877	0.0134**
IMS2	−0.0020	−3.4121	0.0007**
F-statistic = 36.2031 Prob. (F-statistic) = 0.0000**			Adjusted R2 = 0.4552 DW = 1.8324
Panel B: ROA (fixed effects)
Constant	17.6345	2.4481	0.0149*
IMS	0.1204	2.8176	0.0052**
IMS2	−0.0021	−3.6390	0.0003**
SIZE	−1.2114	−2.4861	0.0134**
ΔSALES	0.0231	4.9267	0.0000**
F-statistic = 34.6545 Prob. (F-statistic) = 0.0000**			Adjusted R2 = 0.5025 DW = 1.7998
Panel C: ROE (fixed effects)
Constant	−0.5572	−0.5468	0.5849
IMS	0.1526	2.4835	0.0135**
IMS2	−0.0027	−3.3513	0.0009**
F-statistic = 34.1482 Prob. (F-statistic) = 0.0000**			Adjusted R2 = 0.4404 DW = 1.7891
Panel D: ROE (fixed effects)
Constant	32.2364	3.2302	0.0013**
IMS	0.1722	2.9102	0.0040**
IMS2	−0.0028	−3.6248	0.0003**
SIZE	−2.2277	−3.2996	0.0010**
ΔSALES	0.0319	4.9216	0.0000**
F-statistic = 30.8465 Prob. (F-statistic) = 0.0000**			Adjusted R2 = 0.4965 DW = 1.7917

Note: DW is the Durbin–Watson (1950) statistic, $DW={\sum }_{t=2}^N{({\hat{e}}_t-{\hat{e}}_{t-1})}^2/{\sum }_{t=1}^N{\hat{e}}_t^2$ and ${\hat{e}}_t$ are the least squares residuals from the regression equation under consideration. Based on the Durbin–Watson bounds test, there is no residual autocorrelation if DW is greater than the upper critical value bound, which approximately equals 1.78 at the 5% significance level.

^*Represent the significance level of 5%.

^**Represent the significance level of 1%.